DETERMINATION OF ATTENUATION LENGTHS AND ELECTRON-ESCAPE DEPTHS IN SILICON-NITRIDE THIN-FILMS

Amorphous silicon nitride thin films prepared by low pressure chemical vapor deposition have been investigated by x-ray photoelectron spectr oscopy (XPS) and transmission electron microscopy (TEM). The attenuati on lengths and escape depths of Si 2p photoelectrons with kinetic ener gy of 1385 eV from silicon nitride thin films have been calculated. Hi gh resolution transmission electron microscopy (HRTEM) has been used t o characterize the thin film thickness. The atomic density of Si in th e films decreases with increasing film thickness, leading to a longer attenuation length for thicker films (lambda-degrees almost-equal-to 4 .7 nm for films with thickness of t > 5 nm) than for thinner films (la mbda-degrees almost-equal-to 3.6 nm, t < 4 nm). The attenuation length dependence on the film thickness and experimental setup also provides direct experimental evidence that the simple exponential model for el ectron attenuation may be inaccurate due to elastic scattering effects .